In recent years, personal identification technologies using iris images started to be used in room access control in important facilities, ATMs (automated teller machines) at banks and the like, and PC log-in application and the like. Specifically, the method disclosed in Patent Reference 1 has been already commercialized around the world and is becoming the de facto world standard.
In the method of Patent Reference 1, an iris region is cut out from an image in which an iris is photographed, and the iris region is expressed in polar coordinates. Then, 2D Gabor wavelet filtering is performed to generate an iris code and personal authentication is performed by comparing the iris code generated from the image taken at a time of authentication to an iris code which has been registered in advance.
Moreover, as known techniques for protecting personal privacy, there are techniques for use in surveillance cameras, in which the face or body of a person in an image is obscured by a mosaic or painted out with a color (see, e.g., Patent References 2, 3 and 4).    (Patent Reference 1) Japanese Patent Publication No. 3307936    (Patent Reference 2) Japanese Laid-Open Publication No. 2000-261789    (Patent Reference 3) Japanese Laid-Open Publication No. 2000-278584    (Patent Reference 4) Japanese Laid-Open Publication No. 2001-186507